As discussed in prior related patent applications/patents, referenced hereinabove, as listed hereinabove and incorporated herein by reference, a switch or multiplexer (Mux) is used to couple two or more host ports to a target device. A simple failover switch or Active Passive Mux (APMux) allows two different hosts to connect to the same device, however, when one host is connected to the device, the other host can not access the device. An Active switch or Active Active Mux (AAMux) allows concurrent access by both hosts to the device. “Switch or Mux”, as used herein below, refers to either an Active Switch (AAMux) or a Simple Failover Switch (APMux).
Now, briefly problems associated with current apparatus and method are discussed.
In the case where a target device is a storage device, such as a hard disk drive (HDD), is used, power control becomes an issue in today's technology. More specifically, HDDs are commonly known to hang-up or become nonoperational for a variety of reasons, which are well known in the industry. Upon the occurrence of a hang-up, error recovery is performed in an attempt to render the HDD and the system in which the HDD is being utilized operational. In the event of the error recovery failing, as a last step, recovery of the HDD is performed, requiring turning the power to the HDD ‘off’ and then ‘on’ while the rest of the system in which the HDD is being utilized remains operational.
In light of the foregoing, it is desirable to interrupt power to a HDD without interrupting power to the rest of the system in which the HDD resides, the system including a switch coupling at least two host ports to a target (or storage) device, such as the HDD, and the interruption of power to the HDD being the last step in an error recovery process, initiated from the HDD becoming inoperational.
The SATA and SAS use the same connector, to allow use of either a SATA or SAS device in the same system. SATA uses only one link of the connector whereas SAS uses both links on the connector. That is, when disk drives are used in different settings, the use of a mux may or may not be necessary. A specific example is in the context or application of what is commonly known as “Just a Bunch of Disks” (JBOD), or Disk Arrays which is essentially a large number of removable disks (disk array) or HDDs that are in the same enclosure, connected to a backplane and coupled to a common system interface. In JBODs, using SATA or SAS HDDs interchangeably is desirably. Such JBODs will be referred to as SAS/SATA JBODs. Yet another problem associated with the use of SATA switches on the backplane of SAS/SATA JBOD is the need to bypass the switch on the backplane when a SAS HDD is used.
other systems in a variety of different ways. One way is using the disk array in SATA, another is using the disk array in SAS.
Currently, a disk array JBOD requiring SATA coupling as well as SAS coupling needs two different connections therefor, one for the SATA coupling and another for the SAS coupling. Specifically, SATA uses one link of a connector, whereas, SAS uses both links of a connector and SATA requires a mux, whereas, SAS does not.
Therefore, the need arises for an apparatus and method of bypassing an active switch so as to allow using the same connection to connect two or more host ports on one side of a JBOD to either of the SATA and the SAS target device.